The overall objectives of this proposal are: to determine the characteristic features of brain tumor cell kinetics; to define the principles of cell population proliferative behavior of animal brain tumors in response to therapeutic agents; and, based on cell kinetic analysis, to develop treatment regimens that will improve brain tumor therapy. To accomplish these objectives 9L brain tumor cells in monolayer culture, spheroids and intracerebral 9L tumor will be employed. Perturbations induced by each chemotherapeutic agent will be analyzed by autoradiographic procedures (PLM curves, pulse or continuous labeling, double autoradiography, etc.), flow cytometry, cinephotomicrography and centrifugal elutriation. This systematic attack on the kinetics of perturbed tumor cell populations should lead to the rational development of improved therapeutic regimens for the treatment of malignant brain tumors.